Addition reaction involving diperoxyfumarate and compounds having diperoxysuccinyl groups

ABSTRACT

A DIESTER OF DIPEROXYFUMARIC ACID IS REACTED AT ITS DOUBLE BOND WITH AN ORGANIC COMPOUND R-(X)S WHERE &#34;X&#34; IS A MONOVALENT ATOM READILY ABSTRATABLE BY A FREE RADICAL, E.G., HYDROGEN, CHLORINE OR BROMINE, AND R IS INERT TO THE PEROXYCARBONYL GROUPS OF THE DIPEROXYFUNARATE TO FORM AN ADDITION PRODUCT INCLUDING AT LEAST ONE DIESTER OF A SUBSTITUTED DIPEROXYSUCCINIC ACID. FOR EXAMPLE: TETRAHYDROFURAN AND DI-T-BUTYL DIPEROXYFUMARATE REACT AT ABOUT 0*C. TO FROM DI-T-BUTYL ALPHA-(2-TETRAHYDROFURYL)DIPEROXYSUCCINATE. POLYGLOCOLS AND POLYVINYL ETHERS, ALCOHOLS, HALIDES, ETC. REACT TO GIVE POLYMERS HAVING PENDANT PAIRS OF PEROXYCARBONYL ESTES GROUPS IN GAMMA RELATIONSHIP TO EACH OTHER. THESE COMPOUNDS ARE OF ESPECIAL INTEREST IN THE PREPARATION OF BLOCK AND GRAFT COPOLYMERS.

United States Patent 3,763,112 ADDITION REACTION INVOLVING DIPEROXY-FUMARATE AND COMPOUNDS HAVING DI- PEROXYSUCCINYL GROUPS Richard AnthonyBaiiord, Tonawanda, Ernest Rudolph Kamens, Bulfalo, and Orville LeonardMageli, Kenmore, N.Y., assignors to Pennwalt Corporation, Philadelphia,Pa.

No Drawing. Original application Mar. 8, 1968, Ser. No. 711,502, nowPatent No. 3,592,948. Divided and this application Apr. 2, 1971, Ser.No. 130,855

Int. Cl. C07c 69/00; COSf 1/60, 27/00 US. Cl. 26078.4 D 14 ClaimsABSTRACT OF THE DISCLOSURE A diester of diperoxyfumaric acid is reactedat its double bond with an organic compound R-(X) where X is amonovalent atom readily abstractable by a free radical, e.g., hydrogen,chlorine or bromine, and R is inert to the peroxycarbonyl groups of thediperoxyfumarate to form an addition product including at least onediester of a substituted diperoxysuccinic acid. For example:Tetrah'ydrofuran and di-t-butyl diperoxyfumarate react at about C. toform di-t-butyl alpha-(Z-tetrahydrofuryl)diperoxysuccinate. Polyglycolsand polyvinyl ethers, alcohols, halides, etc. react to give polymershaving pendant pairs of peroxycarbonyl ester groups in gammarelationship to each other.

These compounds are of especial interest in the preparation of block andgraft copolymers.

CROSS-REFERENCE TO RELATED APPLICATION This application is a division ofcopending application Ser. No. 711,502, filed Mar. 8, 1968, now Pat. No.3,592,948.

BACKGROUND OF THE INVENTION (1) Field of the invention This inventionrelates to diesters of substituted diperoxysuccinic acid, which may besimple molecular compounds or polymeric compounds having one or morependant diperoxysuccinyl groups. Also the invention relates to methodsof preparing these compounds.

(2) Description of the prior art We know of no reported work on theaddition reactions of unsaturated peroxyesters.

Free radical additions to olefins to form carbon-carbon bonds are known.Organic Reactions, volume XI-II, devotes two chapters to such additions.It is known that simple maleate esters and simple fumarate esters willundergo such addition reactions to some extent; however, the fumaratesundergo this addition reaction far less readily than do the maleateesters. Thus, Organic Reactions gives 39 examples of maleate esteradditions and only 3 examples of fumarate ester additions.

Patrick, J. Org. Chem, 17, 1009 (1952), reports a 76% yield ofalpha-butyryl succinic ester from the addition of n-butyraldehyde todiethyl maleate; and a 26% yield of alpha-butyryl succinic ester fromthe addition of n-butyraldehyde to diethyl fumarate.

Jacobs and Ecke, J. Org. Chem., 28, 3036 (1963), report a 27% yield ofaddition product of tetrahydrofuran (THF) and diethyl maleate. Maleicanhydride and tetrahydrofuran added at a yield of 61% and 70%. In allthese experiments the temperature was held at the reflux temperature ofthe THF [about 65 0.]. Also, they state the reaction is specific to fivemembered cyclic ethers.

We obtained at the Jacobs and Ecke conditions a 39% yield of theaddition product of diethyl maleate and tetrahydrofuran and a 14% yieldof the addition product of diethyl fumarate and tetrahydrofuran.

SUMMARY OF THE INVENTION We have discovered that diesters ofdiperoxyfumaric acid react with (add to) a great many organic compounds(the more common compounds are simple inert solvents, such as, alcoholsand ethers) when the materials are mixed. The reaction is exothermic andthe tempera ture must be controlled to avoid substantial decompositionof the addition product. (Pure di-t-butyl diperoxy fumarate isindefinitely stable at room temperature, about 25 C.)

This addition reaction is completely unexpected because the simplefumarate esters are rather inert to free radical addition and even undervigorous conditions give poor yield of the addition product (sometimescalled adducts). Even more surprising is the fact that the diesters ofdiperoxyfumarate add more easily and give almost quantitative yields ascompared to maleic anhydride, hitherto considered a very reactivecompound in free radical addition reactions.

To illustrate: Maleic anhydride and THF, at reflux temperature, andsunlamp irradiation, gave a 61% yield of product in 6 hours (Jacobs andEcke). Di-t-butyl diperoxyfumarate and THF, at 0 (zero) C. and sunlampirradiation, gave a yield of 94% of product in 6 hours.

The process of the invention makes a compound having (including) atleast one pair of peroxycarbonyl ester groups in gamma relationship toeach other by saturating the double bond of a diester of diperoxyfumaricacid, under controlled conditions of temperature below about +30 C., bymeans of an organic compound R-(X) where (-X) is present in excess ofthe stoichiometric requirement for saturation of said fumaric acid, toobtain a product including at least one diester of a substituteddiperoxysuccinic acid, where: (a) each of said ester groups is alkyl,cycloalkyl or aralkyl; and (b) R(X) is an organic compound having amonovalent atom -X readily abstractable by a free radical, R is inert tothe peroxycarbonyl groups in said diperoxyfumaric acid diester, and s isequal to at least 1. Desirably the CX bond of compound R-(X) ischaracterized by a bond energy of not more than about kcal. per mole.

Particularly suitable R(X) compounds fall in the classes of alcohols,ethers, aldehydes, formate esters, carboxylic acids, mercaptans,orthoesters, acetals, halohydrocarbons, hydrocarbon substituted silanes,and hydrocarbon substituted phosphines.

The compound of the invention has the formula where (1) R is alkyl,cycloalkyl or aralkyl; (2) R and X are derived from an organic compoundR--(X) X is a monovalent atom readily abstractable by a free radical, Ris inert to a peroxycarbonyl group and s is equal to at least 1; and (3)v" is equal to at least 1 and is not greater than s. Illustrativecompounds are: di-tbutyl alpha-(Z-tetrahydrofuryl)diperoxysuccinate;t-butyl 3-(t-butylperoxycarbonyl)-4-methyl-4-isopropoxy peroxyvalerate;the addition product of equal moles of polyethylene glycol anddi-t-butyl diperoxyfumarate; di-t-butylalpha-(methoxycarbonyl)diperoxysuccinate; and di-t-butylalpha-(N,N-dimethylformamido)diperoxysuccinate.

This invention atfords a surprisingly simple process by which a widevariety of relatively complex organic peroxyesters hitherto unobtainablecan be prepared in good to excellent yields.

The process comprises adding, desirably, a solution of diester ofdiperoxyfumaric acid in a saturated hydrocarbon, such as pentane, orother inert solvent, to an excess, desirably from a 2 to 1 to 20 to 1molar ratio of substrate, -R(X) to fumarate, preferably about 10 to 1,while vigorous agitation is provided and the reaction temperature ismaintained at below about +30, commonly 20 to +30 0., preferably at toC.

The reaction may be irradiated with a sun lamp but this is not necessaryin most cases. Catalysts such as diisobutyryl peroxide, diisopropylperoxydicarbonate or acetyl cyclohexanesulfonyl peroxide may be used inplace of or in addition to a sun lamp.

The peroxyfumarate (solution) is preferably added slowly over a periodof time, for example: over a 4-6 hr. period or even longer. It can beadded all at once if the reaction zone temperature is controlled at thedesired level.

The reaction mixture is stirred for a time, for example: 1 to 2 hours,after completion of the addition of the peroxyfumarate, then the excesssubstrate is removed by suitable means, such as vacuum, stripping,fractional distillation or selective extraction. The addition product isusually substantially pure but may be further purified bycrystallization or the like methods.

Useful substrate, R(X) is any compound having a monovalent atom, X,readily abstractable by a free radical. R is inert to a peroxycarbonylgroup under reaction conditions. The most common abstractable atom X, isa hydrogen atom but other atoms, such as chlorine and bromine, can beabstractable. In general, it may be said that any compound, R-(X) Wherethe bond energy of the C-X bond is not more than about 80 kcal. per molewill be an effective substrate for addition to the double bond of thediperoxyfumarate.

Some illustrations of typical R(X) compounds having a suitable bondenergy are given in Table A.

Other factors must be considered such as stabilization of the radical Rby resonance or hyperconjugation and diffusion of the electron chargeover a large atom such as sulfur or phosphorus,

4 Various classes of compounds R-(X) which are useful, R--(X) is notlimited to these, in the process of the invention are:

(14) molecular arrangements of one or more radicals derived from(1)-(13), said molecules being characterized by the presence of aplurality of (X) atoms, where:

(a) R is hydrogen, alkyl cycloalkyl or aralkyl, each having 1-12 carbonatoms;

(b) R CR may form a homocyclic group;

(0) R is alkyl, cycloalkyl, aralkyl or aryl;

((1) R is hydrogen, alkyl, cycloalkyl, aralkyl or aryl;

(e) R 0-CR may form a heterocyclic group;

(f) R C-R may form a homocyclic group;

(g) R OC-OR may form a heterocyclic group;

(h) R is alkyl, cycloalkyl, aralkyl or halo;

(i) Halo is chloro or bromo;

(j) R is alkyl, cycloalkyl or aralkyl;

(k) R, is hydrogen or C(R H; and

(m) in (1) not more than one R is hydrogen.

The substrate, R-(X) is further illustrated:

( 1) ALCOHOLS Any primary or secondary alcohol, i.e., not more than oneR can be hydrogen, of the defined classes. For example: ethanol,isopropanol, cyclohexanol, and alphaphenethyl alcohol. Moleculararrangement (12) includes simple diols, triols, etc. having two or morehydroxyl groups, such as hexandiol, glycerol and cyclohexandiol.

(2) ETHERS R is alkyl, cycloalkyl, aralkyl or aryl; R is alkyl,cycloalkyl or aralkyl, R OCR may form a heterocyclic system such astetrahydrofuryl, tetrahydropyranyl; R CR may form a homocyclic groupsuch as cyclohexyl, cyclopentyl. Illustrations: diisopropyl ether,phenyl isopropyl ether, t-butyl isopropyl ether, diethyl ether, methylcyclohexyl ether, tetrahydrofuran, Z-methyltetrahydrofuran, poly-etherssuch as polyethylene glycols, polypropylene glycols, Carbowaxes andCarbitols, and simple ether glycols such as diethylene glycol.

(3 ALDEHYDES Illustrations: benzaldehyde, acetaldehyde, formaldehyde,cyclohexanecarboxaldehyde, pivalaldehyde, butyraldehyde,hydrocinnamaldehyde.

(4) KETONES Illustrations: Acetone, di-n-amyl ketone, methyl ethylketone, methyl cyclopropyl ketone, phenyl isopropyl ketone.

(5) FORMATE ESTERS Illustrations: Methyl formate, benzyl formate, phenylformate, and cyclopentyl formate.

(6) CARBOXYLIC ACIDS It is preferred that only one R be hydrogen. Anyacid coming within this class can be used. Simple polycarboxylic acidscome within class (12).

(7) SUBSTITUTED AMIDES Illustrations: N,N-dimethyl formamide;N,N-dimethylisobutyramide, N,N-diethyl formamide.

(8) MERCAPTANS Illustrations: Propanethiol, thiophenol, cyclohexanethioland alpha-mercaptoethylbenzene. Polymercaptans corresponding to glycols,ether glycols, and polyglyeols come within class (12).

(9) ORTHOESTERS Illustrations: trimethyl orthoformate, triphenylorthoforrnate, tricyclohexyl orthoformate, triisobutyl orthoformate.

( 10) ACETALS R is alkyl, cycloalkyl, aryl or aralkyl; R is R orhydrogen; (R O) C can be part of a heterocyclic system such as1,3-dioxolanyl. For example: benzaldehydedimethylacetal,2-phenyl-1,3-dioxolane, butyraldehydediethyl acetal.

(ll) HALOHYDROCARBONS Halo here means chloro or bromo and includes allthose well known members of this class especially the halomethanes,haloethanes, halocyclohexanes, phenyl (chloro)ethane. The chloromethanes and chloroethanes are preferred; however the halowaxes areespecially of interest when a long chain having many pendantdiperoxysuccinyl groups is desired.

(12) HYDROCARBON SUBSTITUTED SILANES Illustrations: trimethyl silane,tribenzoyl silane, tricyclohexyl silane, tri-t-butylsilane.

(13) HYDRO CARB ON SUBSTITUTED PHOSPHINES Illustrations: Dimethylphosphine, di-n-propyl phosphine, di-benzyl phosphine, dicyclohexylphosphine.

(14) MOLECULAR ARRANGEMENTS In addition to the simple polyfunctionalmolecules mentioned in connection with l-13 above, the inventioncontemplates as substrates polymers and copolymers containing the aboveor other functional groups either in the polymer backbone or as pendantgroups. Such addition products are useful for preparation of block andgraft polymers and in polymer laminates where the pendant diperoxysuceinyl groups act as bonding sites between the polymer interfaces.

Illustrative polymer substrates include polymers and copolymers ofpolyvinyl esters, polyacetals, polyethylene glycols, polypropyleneglycols, polyvinyl alcohols, polymethacrylic acids and polyesters ofdiols and dicarboxylic acids.

Substrates containing two or more abstractable hydrogens may be used butcan lead to complex mixtures which will be difiicult to purify.

Substrates containing olefinic unsaturations desirably should be avoidedsince radical reactions will occur at these double bonds to producebyproducts, which may or may not be desirable.

FURTHER ILLUSTRATIVE MATERIAL In order to show the wide variety ofdiperoxysuccinyl group containing simple compounds which can be made bythe process of the invention certain of the above classes are furtherillustrated by compounds, giving a name and the structure deduced by us,using in each instance as one reactant,di-t-butyl-diperoxyfumaratehereinafter designated as DBDPF.

(2) Alkoxy: Tetrahydrofuran and DBDPF. Di-t-butylalpha-(Z-tetrahydrofuryl)diperoxysuccinate O i 5 3 00C 0 3):

H Ii

HzC-C-OOC (CH3)3 (3) Beta-carbonyl: n-butyraldehyde and DBDPF.Dit-butyl, alpha-butyryldiperoxysuccinate (4) Gamma-carbonyl: Methylisopropyl ketone and DBDPF.

t-Butyl 3-(t-butylperoxycarbonyl)-4,4-dirnethyl-S-oxoperoxyhexanoate (5)Carbalkoxy: Methyl formate and DBDPF. Di-t-butylalpha-(methoxycarbonyl)diperoxysuccinate (6) Carboxyl: Isobutyric acidand DBDPF.

t-Butyl gamma-carboxy-gamma-methyl-B-(t-butylperoxycarbonylperoxyvalerate (7) Amido: N,N'-dimethyl formamide and DBDPF.

7 (8) Thiaalkyl: n-propyl mercaptan and DBDPF. Di-t-butyl alpha-(l-thiabutyl) diperoxysuccinate CH OHgCHzS i- O(t-Bu) o H,o-( io O-(t-Bu)(9) Orthoester: Trimethylorthoformate and DBDPF. Di-t-butylalpha-(trimethoxymethyl) diperoxysuccinate H30 0 o GHQO (l-ii-ii-OO-(t-Bu) HzO-CO 0-(t-Bu) Additional definitions Alkyl: Except wherenoted otherwise, each alkyl group may include 1 or more carbon atoms.Desirably each has 1-22 carbon atoms. Preferably each has 1-12 carbonatoms.

Cycloalkyl: May be single ring or have two or more fused rings.Desirably the single ring has in the ring 3-12 carbon atoms, andpreferably 5-8 carbon atoms. Preferably the total number of carbon atomin the radical is 5-12.

Aryl: May be a single benzene ring, or a doubled or higher system, e.g.biphenyl, terphenyl, quaternaphthalene, or a fused benzene ring system,e.g. naphthalene, anthracene, phenathrene, or an alkane bridged system,e.g., biphenylmethane, biphenylpropane. Phenyl, biphenyl, naphthalyl andthe alkyl substituted radicals are preferred.

Aralkyl: The Ar portion of the radical may be as in Aryl. The alkylportion has desirably 1-12 carbon atoms and preferably 1-6 carbon atoms.

R(X) R is any organic radical, preferably free of ethylene unsaturation,inert to peroxycarbonyl groups and having valence bonds equal to s. X isa monovalent atom readily abstractable, under these reaction conditions,by a .free radical. s may be an integer from 1 to about 500, dependingon the type of diperoxysuccinyl compound desired and also the amount ofactive oxygen to be present in the particular product.

Utility As already mentioned the polymeric products of the invention areuseful in graft and block copolymers preparation. All of the products ofthe invention are useful as free radical initiators in the same manneras other peroxyesters and peroxides, for example, in vinylpolymerization and the curing of unsaturated polyester resins andelastomers.

EXAMPLES OF THE INVENTION AND UTILITY Example 1.--The spontaneousdecomposition of Di-tbutyl diperoxyfumarate in diethyl ether A 250 ml.flask was equipped with a reflux condenser, thermometer and magneticstirring bar. The flask was surrounded by an ice bath and to the flaskwas charged 13.0 g. (0.05 mole) of di-t-butyl diperoxyfumarate and 37 g.(0.5 mole) of diethyl ether. When the fumarate ester had dissolvedcompletely, the ice bath was removed and the solution allowed to warmup. The mixture spontaneously warmed up to about 35 and the ether gentlyrefluxed. The mixture was stirred at ambient temperature for sixteenhours.

The ether was removed in vacuo leaving 14.4 g. of a pale yellow viscousoil. The oil was dissolved in a small amount of pentane cooled to andseeded with crystals of di-t-butyl diperoxyfumarate but there was nocrystallization (Pentane is the preferred solvent for therecrystallization of di-t-butyl diperoxyfumarate). The pentane was thenstripped off in vacuo and t e residue was 8 analyzed for active oyygen(the peroxidic oxygen content). The oil contained 7.00% active oxygen.The active oxygen content of pure di-t-butyl diperoxyfumarate is 12.6%.Therefore it was calculated that 37% of the initial active oxygencontent had been lost.

The peroxidic oil (11 g.) was redissolved in 200 ml. of diethyl etherand stirred at ambient temperature .for 24 hours. The ether was removedin vacuo as before leaving 10 g. of yellow oil. The oil was analyzed andwas found not to have lost any further active oxygen.

Thus it is apparent that the peroxidic oil was not impure di-t-butyldiperoxyfumarate since after the initial loss of active oxygen nofurther loss occurred on prolonged stirring with a fresh quantity ofdiethyl ether.

Example 2.-The decomposition of di-t-butyl diperoxyfumarate in ethylalcohol A 0.1 molar solution of di-t-butyl diperoxyfumarate in ethanolwas prepared by the dissolving the required amount of fumarate ester inethyl alcohol at 10 C. The solution was kept below 0 C. Ten ml. aliquotsof the solution were sealed in tubes and placed in a constanttemperature batch at 40. Samples were removed periodically and assayedfor active oxygen and for unreacted di-t-butyl diperoxyfumarate by thinlayer chromatography. Within one hour of placing the tubes in the bath,all of the di-t-butyl diperoxyfumarate had disappeared even though therewas very little loss of active oxygen.

Thus it is evident that some reaction took place between ethanol anddi-t-butyl diperoxyfumarate that did not involve the peroxidic oxygenatoms.

Example 3.The preparation of di-t-butyl alpha-(2- tetrahydrofuryl)diperoxysuccinate A 200 ml. reaction kettle was fabricated having thefollowing specifications: internal diameter 1.5 inches, in ternal height7 inches and reactor completely enclosed in a glass jacket for thepurpose of circulating a heat exchange liquid usually ice water. Thereactor was equipped with a mechanically-operated paddle stirrer, areflux condenser, thermometer, and an additional .funnel. The reactorwas irradiated by a Westinghouse 275 watt .sun lamp situated about 10inches from the outer wall of the reactor.

The reactor was charged with ml. of tetrahydrofuran freshly distilledfrom lithium aluminum hydride. A saturated solution of 39 g. (0.15 mole)of di-t-butyl diperoxyfumarate in pentane was placed in the additionfunnel. The funnel Was covered with aluminum foil to prevent irradiationof the diperoxyfumarate solution. The air in the reactor was displacedby nitrogen. The sun lamp was turned on and dropwise addition of the.fumarate solution was begun. The addition required five hours and therewas an additional 30 minutes of stirring after addition was complete.The reaction temperature was maintained at l-2 C. by circulating icewater through the reactor jacket.

The reaction mixture was then stripped on a rotating vacuum evaporatorat 25 and 0.1 mm. pressure until there was no further weight loss.

The residual oil weighed 46.7 g. (94% of theory) and contained 894%active oxygen. The theoretical active oxygen for di-t-butylalpha-(2-tetrahydrofuryl)diperoxysuccinate is 9.64%. The assay based onactive oxygen was therefore 92.8%.

A duplicate run made under identical conditions gave 47.2 g. (94.8% oftheory) and an active oxygen content of 8.83%. (91.6% of theory).

In order to establish the structure of the product, a 10 gram sample wasdissolved in 50 ml. of absolute alcohol and subject to hydrogenolysis at50 p.s.i.g. and 25 C. using a 1% platinum on charcoal catalyst in a Parrhydrogenation apparatus. Peroxyesters are readily reduced to the parentacid and the alcohol from which the peroxy portion ofthe ester wasderived.

After no further hydrogen was absorbed, the ethanolic solution wasfiltered to remove the catalyst and the filtrate was stripped in vacuoon a rotating evaporator, leaving a solid residue weighing 4.2 g. Thesolid was triturated with benzene, filtered and dried twelve hours in avacuum oven at 50 C. The solid melted at 128-33 C. on a Fisher-Johnsmelting point block. The neutralization equivalent was found to be 99.8.The theoretical value for alpha-(Z-tetrahydrofuryl)succinic acid is94.1.

Since this acid has not been disclosed in the literature, an authenticsample was prepared by the saponification of diethylalpha-(Z-tetrahydrofuryl)succinate which was prepared by the addition oftetrahydrofuran to diethyl maleate. The authentic acid after beingrecrystallized twice from a chloroform-cyclohexane solution melted at128-130. The free acid has a tendency to absorb moisture from the air. Acarefully dried sample had a neutralization equivalent of 94.1 (theory94.2). The infrared spectra of mineral oil mulls of the authentic acidand the acid obtained by hydrogenolysis of the perester were identical.

Example 4.The preparation of di-t-butyl alphaacetyldiperoxysuccinateInto the reactor described in Example 3 was charged 88 g. (2.0 moles) ofacetaldehyde. The reactor was irradiated by the sun lamp. A saturatedsolution of 39.0 g. (0.15 mole) of di-t-butyldiperoxyfumarate in pentanewas added over a 7 hour period to the stirred acetaldehyde while thereaction temperature was kept at After the addition was complete, thereaction mixture was stirred for 30 minutes.

The reaction mixture was stripped in vacuo of excess acetaldehyde on arotating evaporator. The residue which weighed 66 g. was dissolved in200 ml. of diethyl ether and W; extracted six times with 100 ml.portions of water. The water washings were discarded and the etherealsolution was dried over magnesium sulfate. The drying agent was removedby filtration and the filtrate was stripped in vacuo on a rotatingevaporator. The residue was a pale yellow oil, weighed 41.9 g. (92% oftheory), and assayed 74.8% based on active oxygen.

A drop of the yellow oil when added to a dilute aqueous ferric chloridesolution showed the deep red color characteristic of Beta-ketoesters.Neither acetaldehyde nor di-t-butyl diperoxyfumarate give this color.

A 10 g. portion of peroxide was subject to hydrogenolysis as describedin Example 3. A platinum oxide catalyst was used instead of platinum oncharcoal when it was observed that addition of the platinum catalystcaused violent decomposition of the peroxide. This characteristicproperty was observed with all alpha-acyl-diperoxysuccinates that wereprepared. Neither di-t-butyl diperoxyfumarate nor the adducts derivedfrom substrates other than aldehydes were decomposed by platinum oncharcoal.

Filtration and evaporation of the hydrogenolysis mixture left an oilyliquid acid having the properties of levulinic acid. The expectedhydrogenolysis product alphaacetylsuccinic acid is unstable and rapidlyloses carbon dioxide to give levulinic acid. Beta-keto-carboxylic acidsare prone to decarboxylation.

Example 5 .-The preparation of di-t-butyl alphabutyryldiperoxysuccinateThe reactor described in Example 3 was charged with 150 ml. of freshlydistilled n-butyraldehyde. The sun 10 lamp was turned on and a pentanesolution containing 39.0 g. (0.15 mole) di-t-butyl diperoxyfumarate wasadded over a 5.5 hour period to the butyraldehyde maintained at 0 C.Stirring was continued for two hours after completion of the addition.

The reaction mixture was stripped at room temperature on a rotatingevaporator at an ultimate vacuum of 0.1 mm. The colorless residueweighed 51.9 g. (104% of theory) and assayed 87.2% based on activeoxygen.

A 5 gram sample was hydrogenolyzed using a platinum oxide catalyst asdescribed in Examples 3 and 4. After removal of the catalyst andsolvent, there remained a low-melting colorless solid. Recrystallizationfrom cyclohexane afforded 1 g. of shiny crystals melting at 47 andhaving a neutralization equivalent of 146.1. The theoreticalneutralization equivalent of 4-oxoheptanoic acid is 144.2 and thereported melting point is 49-50, Wiley and Herrell, J. Org. Chem. 25,903 (1960). Alphabutyrylsuccinic acid spontaneously decarboxylates to 4-oxoheptanoic acid.

A 30 g. sample of the crude di-t-butyl alpha-butyryldiperoxysuccinatesolidified on standing two weeks in a refrigerator. The solid wasrecrystallized from pentane at 0 C. The colorless crystalline productmelts at 30 C. and assayed 96.0% based on active oxygen.

Example 6.The addition of diisopropyl ether to di-tbutyldiperoxyfumarate The reactor described in Example 3 was charged with 102g. (1.0 mole) of diisopropyl ether and was illuminated by a sun lamp.The ether was vigorously stirred under a nitrogen atmosphere while apentane solution containing 26.0 g. (0.1 mole) of di-t-butyldiperoxyfumarate was added over a period of 6.5 hours. The reactionmixture was stirred for an additional hour. The temperature was kept at0 to 2 during the reaction.

The excess diisopropyl ether and pentane were removed in vacuo on arotating evaporator. The liquid residue weighed 31.0 g. (86% of theory)was assayed 83.9% based on active oxygen.

Hydrogenolysis over a platinum on charcoal catalyst of 12 g. of theadduct gave a very hygroscopic solid dicarboxylic acid having aneutralization equivalent of 110.3 The acid was identified as3-carboxy-4-methyl-4-isopropoxyvaleric acid -(I) having a theoreticalneutralization equivalent of 109.12.

The new peroxide therefore is t-butyl 3-(t-butylperoxycarbonyl)-4-methyl-4-isopropoxyperoxyvalerate (II) arising fromthe addition of a molecule of diisopropyl ether across the double bondof di-t-butyl diperoxyfumarate.

CH; CH; 0 l H II H |3-0oc-c-oH CH: CE: (I?

HzC-C-OH OH; CH, 0 I H II H?O(l]-C-C0 0 C(CHa):

CH5 CH3 (I? H2C-C-O O C(CH3)I Example 7.The addition of polyethyleneglycol to di-tbutyl diperoxyfumarate Into the reactor described inExample 3 was charged g. of Polyglycol E600, a product of the DowChemical Corporation consisting of a polyethylene glycol having a numberaverage molecular weight of 600. The air in the reactor was displacedwith nitrogen. The reactor was irradiated by a sun lamp while a pentanesolution of 43.3 g. (0.167 mole) of dit-butyl diperoxyfumarate was addedover a 5.5 hour period. The reaction mixture was maintained at 24 C.,the lowest temperature at which the mixture remained liquid. After atotal reaction time Of 7 hours, the mixture was transferred to an opentop reactor and extracted twice with 100 ml. portions of pentane inorder to remove any unreacted peroxyfumarate ester. The second extractcontained no measured active oxygen.

The reaction mixture was stripped at an ultimate vacuum of 0.1 mm. on arotating evaporator. The residue weighed 127.8 g. and contained, byiodometric titration, 2.99% active oxygen. This corresponds to a 72%yield based on active oxygen content.

The structure of this product is shown below, where m-l-n is 10 to 16.

Example 8.The addition of isopropyl alcohol to di-tbutyldiperoxyfumarate A pentane solution of 39.9 g. (0.15 mole) of di-t-butyldiperoxyfumarate was added over a 6.5 hour period to 120 g. (2.0 mole)of isopropyl alcohol contained in the reactor described in Example 3.The reactor was illuminated by a sun lamp and kept at during theaddition and for a further 90 minutes of stirring.

A solid product began to separate from the reaction mixture toward theend of the reaction. The reaction mixture was concentrated in vacuo toone-half its volume and then kept at 0 for two hours during which acolorless solid crystallized. The product was separated by filtration,the filter cake washed with a little cold isopropyl alcohol and dried bypassing air through the filter cake. The solid melted at 65-70" andweighed 12 g. Additional product was isolated by concentrating themother liquors.

The isopropyl alcohol mother liquors contained t-butyl hydroperoxideindicating that some transesterification had occurred during thereaction as shown in equation.

CH3 HO J-CH- O O (X0113):

HzC--O 0 C(CH3)3 (III) (CHa)zCHOH CH3 0 CH3 (CHa)aC O OH CH OH;

CH: C 3

HzC- -OOC(CH )a by spontaneous lactonization of the diacid as shown inequation.

The neutralization equivalent for VI was found to be 162 (theoreticalvalue is 15 8). A portion of VI was carefully saponified with warmaqueous sodium hydroxide and the excess base was back-titrated with 0.1N acid using a pH meter to determine the end point. The saponificationequivalent (after correction for the free carboxylic acid) was found tobe 168 (theory for VI is 158).

Example 9.-The preparation of di-t-butyl alphapivaloyldiperoxysuccinateThe title compound was prepared by adding a pentane solution of 39 g.(0.15 mole) of di-t-butyl diperoxyfumarate to 100 g. (1.16 mole) ofpivalaldehyde (trimethylacetaldehyde) under conditions equivalent tothose described in Example 5. From the vacuum-stripped crude reactionmixture was isolated 16.9 g. of crystalline di-tbutylalpha-pivaloyldiperoxysuccinate (VII) melting at 6 5 and assaying 103%based on the active oxygen" content. Additional product of slightlylower assay was isolated from the mother liquors.

0 HzC( J0OC(OH )r (VII) Example 10.The preparation of di-t-butyl alpha-(methoxycarbonyl diperoxysuccinate A pentane solution of 39.0 g. (0.15mole) of di-t-butyl diperoxyfumarate was added over a six hour period toml. of methyl formate contained in the reactor described in Example 3.The reactor was illuminated by a sun lamp and kept at 0-5 C. during theaddition and for a further 90 minutes of stirring.

The reaction mixture was stripped on a rotating evaporator to anultimate vacuum of 3 mm. in order to remove the pentane and unreactedmethyl formate. The residue weighed 38.8 g. (81% of theory) and assayed100% based on active oxygen determination.

An 8 g. sample was hydrogenolyzed using a platinum on charcoal catalyst.Work-up of the reaction mixture yielded an oily solid which was purifiedby precipitating it from acetone by the addition of pentane. Theneutralization equivalent of the solid was 69 (theory for VIII is 88;theory for IX is 54). Therefore, the hydrogenolysis product is probablya mixture of VIII and IX.

13 14 One g. of the hydrogenolysis product was heated on a Example13.The addition of trimethyl orthoformate to steam bath for 1 hour with15 ml. of water containing 2 di-t-butyl diperoxyfumarate drops ofconcentrated hydrochloric acid until the mix- A pentane Solution of 39 g(015 mole) of di t buty1 ture was completely homogeneous. The yellowsolution was evaporated to dryness leaving a semicrystalline solid. 5106 0. (1.0 mole) of trimethyl orthoformate contained This solid wasdissolved in ethyl acetate and reprecipiin reactor described in Example3 The reactor was tated by the addition of ether. The colorlesscrystalline illuminated by a Sun lamp and kept i c during solid wasremoved by filtration, washed with a little ether the addition and for afurther 1% hours of stirrilig and air'dried' The iolid F withdecomposition at The reaction mixture was stripped at an ultimate vac-177-1780 The meltmg pomt reported for uum of 1 mm. using a rotatingevaporator leaving a vistricarboxylic acid (IX) 13 178, Bull. Soc. Chem.France, cons yellow Oil weighing 363 (66% of theory) anddiperoxyfumarate was added over a 5.5 hour period to 19 assaying 84 2%based on active ox ygen content. The The peroxidic product is thereforedi-t-butyl alpha- Structure f the product is Shown below (XIII)(methoxycarbonyl)diperoxysuccmate (X). OCH 0 .5 t O H CHgO CH -OOC(CH:):CH30&C-OOC(CHK)3 CH3 0 0 H2 -OOC(CH H2 Ji-ooowmn 20 (XIII) (X) Example14.-Preparation of a polyethylene glycol-Polystyrene graft copolymer Thepolyethylene glycol-di-t-butyl diperoxy fumarate adduct described inExample 7 was used to initiate A pentane solution of 39.0 g. (0.15 mole)of di-t-butyl styrene polymerization at 100 C.

Example 11.The addition of methyl isopropyl ketone to di-t-butyldiperoxyfumarate diperoxyfumarate was added over a 4 hour period to 129At an initiator concentration of 5 10 active oxygen g. (1.5 moles) ofmethyl isopropyl ketone contained in equivalents per deciliter ofstyrene the rate of initiation the reactor described in Example 3. Thereactor was ilwas 9.66 10- mole/liter/rnin. as determined by luminatedby a sun lamp and kept at 0 C. during the dilatometry.

addition and for a further 3 hours of stirring. The resultant polymerwas a mixture of polystyrene The reaction mixture was then stripped atan ultimate homopolymer and a polyethylene glycol-polystyrene graftvacuum of 0.1 mm. on a rotating evaporator leaving 45.2 copolymer withthe probable structure (XIV) shown g. (86.5% of theory) of a pale yellowliquid containing below where m+n=l0 to 16, x and y are from 10 to 500.

HO CHzCHg(O CHzCHzhO CHCIIAO CHzOHg)mO CH CHgOH C|H5 Cs 5 Ce 5 05 59.11% active oxygen (theory for (XI) 9.24%). Assay The polystyrenehomopolymer was removed by exwas therefore 98.7%. traction with benzenein which the graft copolymer is insoluble. i E Example 15 CH3 In orderto demonstrate the capability of this process 0 to tailor-make peroxidesof a desired decomposition rate, the half-lives of several of theperoxides, described H CH C-OOC CH 2 m in the preceding examples, weredetermined. Dilute ben- (XI) zene solutions, usually 0.1 molar, of theperoxides were Example 12.The addition of isobutyric acid to prepared,aliquots were sealed into glass tubes and the di-t-butyldiperoxyfumarate glass tubes were immersed in constant temperaturebaths.

Samples were periodically withdrawn and were assayed for active oxygencontent by standard analytical methods. All the peroxides tested folowedfirst order decomposition kinetics. The half-lives are listed in Table15.

A pentane solution of 39.0 g. 0.15 mole) of di-t-butyl diperoxyfumaratewas added over a 7 hour period to 132 g. (1.5 moles) of isobutyric acidcontained in the reactor described in Example 3. The reactor wasilluminated by a sun lamp and kept at 0 C. during the addition and for af the 15 minutes of i i TABLE 15.-SELECTED HALF-LIVES or PEROXIDES Thereaction mixture was stirred into 800 ml. of ice Temp water. The organiclayer was separated and washed 4 Sample -l times with 500 ml. portionslof water. {The organic layer A Di t.buty1djper0xyfun arate 185 wasdiluted with an e ual vo ume of et er and dried over sodium sulfate. Thes lution, filtered free of drying agent, B 352L 55;3.123%: 85 wasstripped in vacuo on a rotating evaporator to a C gggggg 35 Weight of 64g. Since the theoretical yield was 52.3 g., 100 9, there was stillunreacted isobutyric acid in the product. DDic'itrlggylalpha'pivfiloyldiperoxysuc 85 The water etxraction procedurewas repeated and the 65 E Di-t-butyld1peroxyfumaratepolyethylene 100 5.5product after drying and stripping we1ghed 37 7 g. (72% F ib g iggg 85we of theory) and assayed 80.3% based on active oxygenmethyl-Msopropoxyperoxyvalerate. content. The structure of the productis shown below (XII).

0 3 0 Example 16 H I Rates of polymerization of styrene were determinedby Ho lgc flooc(cm)a dilatometry using the peroxides listed in Table 15as CH3 initiators. The concentration of initiator was 5 10-HrC-d-00C(CH,); active oxygen equivalent per deciliter of styrene. There- (XII) 7 sults are listed in Table 16.

TABLE 16.PEROXIDE-I %%l}lj) POLYMERIZATION or Example 19.Addition ofN,N-dimethylformamide to di-t-butyl diperoxyfumarate Rate ofPolymerpo1ymeriza- A pentane solution of the diperoxyfumarate was addedfggg f gg gg g? over a five hour period to N,N-dimethy1 formamide, the

Peroxide ture, m m 5 reaction zone was maintained at 0 C. The reactionprod- Sflmple degree minute uct mixture was diluted with water and theaddition prod- 85 4.51xuct extracted with benzene; the extract was driedover igg gggfigj magnesium sulfate and stripped in vacuo. The product 85534x10 was an amber oil which is very unstable at room temper- 0 ature.The roduct has the structure: Example 17.-The heterogeneous additionreaction of a p polyvinyl ether and di-t-butyl diperoxyfumarate E Aslurry of 17 parts by a weight of Gantrez resin (a O o-(t'Bu) copolymerof methyl vinyl ether and maleic anhdyride, a 0 Hz product of theGeneral Aniline and Film Corporation), A

17 parts di-t-butyl di-peroxyfumarate and 66 parts of benzene wasstirred for 7 hours at 23 while being irradiated a -0 O-(t-Bu) with asun lamp. (XVII) The Slurry was filtered and the Solids Were Washed Thushaving described the invention, what is claimed is:

well with benzene to remove any unreacted di-t-butyl di- 1. A processfor preparing a substituted diperoxy peroxyfumarate. The solid polymericproduct was found cinic acid diester of the formula to contain 0.09%active oxygen corresponding to an adduct containing 1.9 g. of di-t-butyldiperoxy fumarate and 98.1% g. of Gantrez resin. A control run in whicha)aCO C (CHa)8 no diperoxyfumarate was added contained no detectable 25active oxygen which process comprises saturating the double bond of a Inanother run, a slurry of 88.2 parts hexane, 9.8 parts Gantrez resin and2.0 parts of di t ,butyl diperomh d1ester of diperoxyfumarlc acid of theformula fumarate was used. A polymeric product was isolated f 6containing 0.11% active oxygen. (CHa)aC-OOCO=OC-O 0c(cH.)a

We believe the product to be formed by a free radical addition involvingthe carbon-hydrogen bonds adjacent to the ether oxygens in the resin togive structure XV shown below.

at a temperature in the range of about 20 C. to +30 C. by means of theaddition of a polymer, RH, which contains a readily extractable hydrogenatom and is se- Example 18.-The homogeneous addition reaction of lectedfrom polyethylene glycol, polyvinyl ether and polya polyvinyl ether orpolyvinyl acetate and di-t-butyl vinyl acetate. diperoxyfumarate 2. Aprocess comprising reacting polyethylene glycol um lecular weight ofabout 600 (a) A solution of 92 arts of acetone, 6.6 parts of 5 halvmg nbet i mo Gantrez resin and parts of di t butyl (penny with di-t-butyldiperoxyfumarate 1n about equimolar fumarate was stirred for 5 hours at23 while being irradamounts Said, fumarate, being added in form i aiated with a sun lamp pentane solution, to said glycol over a perlod oftime The Product was Precipitated by pouring the acetone whilemaintaining the reaction zone temperature of about solution into anexcess of hexane. The precipitated amifecovermg mactlon prPduct polymerwas Separated by filt ti The polymer was ture an add1t1on product ofsaid glycol and said fumarate purified by dissolving it in acetone andreprecipitating it havmg Pendant P at least one Carbon atom a (1141'from hexane. After two precipitations, the polymer was butyldlpel'oxysuccmyl p: analyzed for active oxygen. The polymer contained0.16% active oxygen. The polymer from a control run I contained nodetectable active oxygen. (OHmCOOC(O)OHGH2C(0)O0C(CH (b) A similarreaction was carried out with polyvinyl acetate instead of Gantrezresin. The resultant olymer was found to contain 0.11% active oxygen. Onof the process compnsmg reactplg Polyvmyl, acetate Structures (XVI) ofthe polymeric product is Shown and di-t-butyl diperoxyfumarate, inacetate solution, at a below temperature of about 23 0., and recovermgfrom the (CH) C O O O 0 Cum) reaction product mixture a polymer havingactive oxygen 5 a a 3 derived from at least one pendant di-t-butyldiperoxysuc- (3:0 cinyl group.

H( |lCHa c 4.

9H: lHa (IJH: CH;

(XVI) Where ml-l-n is 10-16.

where x+y has a combined value such that the polymer has an activeoxygen content of about 0.11 percent.

6. A process for preparing a substituted diperoxy succinic acid diesterof the formula which comprises saturating the double bond of a diesterof diperoxyfumaric acid of the formula at a temperature in the range ofabout -20 to +30 C. by means of the addition of a polymer, RH, which isfree of olefinic unsaturation, contains a readily extractable hydrogenatom and is selected from the group consisting of polymers of polyvinylesters, polyvinyl ethers, polyacetals, polyethylene glycols,polypropylene glycols, polyvinyl alcohols, polymethacrylic acids andpolyesters of diols and dicarboxylic acids, where R is inert to aperoxycarbonyl group and R is tertiary alkyl, tertiary cycloalkyl ortertiary aralkyl.

7. A polymer of the formula moocmmmouommom where:

R is t-alkyl, t-cycloalkyl or t-aralkyl; and R is a polymeric residuewhich is inert to a peroxycarbonyl group resulting from the extractionof a hydrogen atom from a polymer, RH, which is free of olefinicunsaturation and is selected from the group consisting of polymers ofpolyvinyl esters, polyvinyl ethers, polyacetals, polyethylene glycols,polypropylene glycols, polyvinyl alcohols, polymethacrylic acids andpolyesters of diols and dicarboxylic acids. 8. Claim 7 where R istertiary butyl. 9. A polymer according to claim 8 where RH ispolyethylene glycol.

10. A polymer according to claim 8 where RH is polyvinyl acetate.

11. A polymer according to claim 8 where RH is polyvinyl ether.

12. A process for prepa r ir i g a substituted diperoxy succinic aciddiester of the formula 0 H H 0 RH) o-ii-d-c'a-ii-o Mt.

which process comprises saturating the double bond of a diester ofdiperoxyfumaric acid of the formula OHHO llllll References Cited UNITEDSTATES PATENTS 3,536,676 10/1970 Mageli et al. 26078.5

2,567,615 9/1951 Milas 260-453 2,577,133 12/1951 Ladd 260-483 2,698,8631/1955 Dickey 260-453 FOREIGN PATENTS 1,041,088 9/1966 Great Britain.

OTHER REFERENCES Yurzhenko et al., Synthesis of Peroxide Esters ofAliphatic Dibasic Acids, Journal of Organic Chem. of the U.S.S.R., vol.1, January-April, pp. 689-91.

Patrick, Jr., The Free Radical Addition of Aldehydes to UnsaturatedPolycarboxylic Esters, pp. 1009-16, 1952.

Walling et 211., Free Radical Addition to Olefins to Form Carbon-CarbonBonds, 1963, pp. 112-13, 118, 120-21, 132-4, 139, 147-49, Chap. 3 and 4.

Ivan Chov et al., Some Di-Tert-Butylesters, etc. 1967, CA67, 22266b.

JOSEPH L. SCHOFER, Primary Examiner J. KIGHT, Assistant Examiner US. Cl.X.R.

252-434; 260--78.4 E, 78.5 B, C, 89.1, 89.55, 91.1 S, 91.3 VA, 333,347.4, 347.5, 453 K, P, AR, A1, 610 D, 861, DIG. 28

